Structuring of glassy carbon (GC) can be performed by various methods such as sawing, laser ablation, and reactive ion etching (RIE). Laser machining with a tripled Nd:YAG laser at an irradiation wavelength of 355 nm allows the fabrication of V-shaped channels with depths > 600 mum and aspect ratios > 5. This method is very flexible for rapid prototyping, but is comparatively slow due to the sequential machining. A complete flowfield consisting of 100 parallel channels with a depth of 250 mum and a top width of 50 mum was prepared by direct laser ablation and tested in a micro fuel cell. As an alternative, a novel process combining laser structuring of a metal mask with subsequent reactive ion etching was developed. The quality of the metal layer and the ablation behavior are strongly influenced by the metal adhesion, which depends on the GC pretreatment and the deposition technique. Reactive ion etching of glassy carbon can be performed with etch rates of approximate to 40 mum h(-1), but the high pressure conditions of 100 mTorr (0.13 mbar) limit the aspect ratio to < 1.5 due to pronounced underetching. The fabrication of structures with aspect ratios > 4 and etch rates of approximate to 10 mum h(-1) is possible with the use of alternative etching devices with different design or plasma sources. (C) 2003 Elsevier B.V. All rights reserved.